Stefaan Mulier1, Ricardo Possebon2, Yansheng Jiang3, Jacques Jamart4, Chong Wang2, Yi Miao5, Tongfu Yu5, Kuirong Jiang5, Yuanbo Feng3, Guy Marchal3, Luc Michel6, Yicheng Ni7. 1. Department of Surgery, Delta Hospital, CHIREC Cancer Institute, Triomflaan 201, 1160, Brussels, Belgium; Department of Radiology, Gasthuisberg University Hospital, Herestraat 49, 3000, Leuven, Belgium. 2. Alegrete Technology Center, Federal University of Pampa, Av. Tiarajú 810, Ipirabuitã, CEP 97546-550, Alegrete, Rio Grande do Sul, Brazil. 3. Department of Radiology, Gasthuisberg University Hospital, Herestraat 49, 3000, Leuven, Belgium. 4. Department of Biostatistics, Mont-Godinne University Hospital, Avenue du Dr. Thérasse 1, 5530, Yvoir, Belgium. 5. Department of Surgery and Radiology, First Hospital of Nanjing Medical University, Guangzhou Road No 300, 210029, Nanjing, China. 6. Department of Surgery, Mont-Godinne University Hospital, Avenue du Dr. Thérasse 1, 5530, Yvoir, Belgium. 7. Department of Radiology, Gasthuisberg University Hospital, Herestraat 49, 3000, Leuven, Belgium. Electronic address: yicheng.ni@kuleuven.be.
Abstract
PURPOSE: Radiofrequency ablation (RFA) is increasingly being used to treat unresectable liver tumors. Complete ablation of the tumor and a safety margin is necessary to prevent local recurrence. With current electrodes, size and shape of the ablation zone are highly variable leading to unsatisfactory local recurrence rates, especially for tumors >3 cm. In order to improve predictability, we recently developed a system with four simple electrodes with complete ablation in between the electrodes. This rather small but reliable ablation zone is considered as a building block for matrix radiofrequency ablation (MRFA). In the current study we explored the influence of the electric mode (monopolar or bipolar) and the activation mode (consecutive, simultaneous or switching) on the size and geometry of the ablation zone. MATERIALS AND METHODS: The four electrode system was applied in ex vivo bovine liver. The electric and the activation mode were changed one by one, using constant power of 50 W in all experiments. Size and geometry of the ablation zone were measured. Finite element method (FEM) modelling of the experiment was performed. RESULTS: In ex vivo liver, a complete and predictable coagulation zone of a 3 × 2 × 2 cm block was obtained most efficiently in the bipolar simultaneous mode due to the combination of the higher heating efficacy of the bipolar mode and the lower impedance by the simultaneous activation of four electrodes, as supported by the FEM simulation. CONCLUSIONS: In ex vivo liver, the four electrode system used in a bipolar simultaneous mode offers the best perspectives as building block for MRFA. These results should be confirmed by in vivo experiments.
PURPOSE: Radiofrequency ablation (RFA) is increasingly being used to treat unresectable liver tumors. Complete ablation of the tumor and a safety margin is necessary to prevent local recurrence. With current electrodes, size and shape of the ablation zone are highly variable leading to unsatisfactory local recurrence rates, especially for tumors >3 cm. In order to improve predictability, we recently developed a system with four simple electrodes with complete ablation in between the electrodes. This rather small but reliable ablation zone is considered as a building block for matrix radiofrequency ablation (MRFA). In the current study we explored the influence of the electric mode (monopolar or bipolar) and the activation mode (consecutive, simultaneous or switching) on the size and geometry of the ablation zone. MATERIALS AND METHODS: The four electrode system was applied in ex vivo bovine liver. The electric and the activation mode were changed one by one, using constant power of 50 W in all experiments. Size and geometry of the ablation zone were measured. Finite element method (FEM) modelling of the experiment was performed. RESULTS: In ex vivo liver, a complete and predictable coagulation zone of a 3 × 2 × 2 cm block was obtained most efficiently in the bipolar simultaneous mode due to the combination of the higher heating efficacy of the bipolar mode and the lower impedance by the simultaneous activation of four electrodes, as supported by the FEM simulation. CONCLUSIONS: In ex vivo liver, the four electrode system used in a bipolar simultaneous mode offers the best perspectives as building block for MRFA. These results should be confirmed by in vivo experiments.
Authors: Louisa Bühler; Markus D Enderle; Nicolas Kahn; Markus Polke; Marc A Schneider; Claus Peter Heußel; Felix J F Herth; Walter Linzenbold Journal: Biomedicines Date: 2022-05-10